My boat since day 1 has been plagued with overflow issues from the check valve. The check valve is a one way valve that lets the gas tank "Vent" but not suck in water. The problem is the vent sits atop the gas tank and the vent hole on the side of the boat is either at the same height or lower then the vent on the tank. I installed a plastic check valve a while back but it didn't seem to do much. I still have gas spewing out the side of my boat when I have a full tank and go around a right hand corner.
I'm asking for some advice on the proper way that a check valve system should be run or installed. I'm tired of having gas run down the side of the boat and eat away my decals ect.
Thanks in Advance
"G

So the Idea will be to try and run the over flow line as close to the underside of the deck (highest point) and then back down and up to the over flow in the back. I know in the drawing Im showing the line running line 90's but it will swoop I dont like the Idea of gas sitting in the low point of the line. Can I run the Valve in a horizontal position???

The first example is the correct way. The valve has a ball inside that must be at a 55 angle to flow (roll) and seal properly.
I dont know if you can see the photos in this link but it will give you a good visual.

Looks like the check Valve you recommended is no longer available from Skidim
I got this email from them after I placed the order.

The Air/Fuel separator you ordered has been superseded with a less expensive, good alternative product, cost is just $24.99.
Item #31612. We no longer have the expensive one in stock. May we substitute for you?

I have the Attwood one right now. That's the cheeper one they are referring to.
Any ideas on another source